Heat pump temperature control device for motor vehicle

ABSTRACT

The device includes a heat pump integrating a refrigerant circuit taking calories from a cold source to transfer them towards a warm source. The device also includes a heat-conducting fluid/air thermal exchanger called external exchanger ( 30 ), located in the vehicle engine compartment ( 34 ), the heat-conducting fluid being either the refrigerant or a heat-conducting fluid in thermal exchange with the cold source refrigerant. The device also includes means of formation of an air flow, preferably a fan ( 40 ), circulating through the external exchanger ( 30 ) and called outlet air flow, directed from inside the engine compartment ( 34 ) to outside the vehicle. Preferably, the fan ( 40 ) shall be able to rotate in a first direction to form an air flow directed from outside the vehicle to inside the engine compartment ( 34 ) and called inlet air flow, and in a reverse direction to form the outlet air flow.

This invention relates to a heat pump based thermal regulation devicefor automotive vehicles.

It is already known in the state of the art, especially according toFR-2 697 210, a process of thermal regulation for automotive vehicles ofthe type including:

-   -   a heat pump including a compression refrigerant circuit taking        calories from a cold source to transfer them at least partially        towards a warm source, and    -   a heat-conducting fluid/air thermal exchanger, called external        exchanger, located in the vehicle engine compartment, the        heat-conducting fluid being either the refrigerant or a        heat-conducting fluid in thermal exchange with the cold source        refrigerant.

The compression circuit generally includes an evaporator, in thermalexchange with the cold source, and a condenser, in thermal exchange withthe warm source, these elements being connected to each other by acompressor and a regulator. The refrigerant vaporises in the evaporatorby taking the heat from the cold source. The compressor pumps thevaporised refrigerant in and pumps it out in the cooled condenser (bythermal exchange with the warm source) in which it condenses. Theregulator lets the liquid refrigerant flow towards the evaporator bydecreasing its pressure.

A heat pump can be used either to heat a space or a component or to coolthis space or component.

In FR-2 697 210, on the one hand, the cold source includes a firstrefrigerant/heat-conducting fluid thermal exchanger thermally couplingthe refrigerant circuit, forming a main circuit, to a first secondaryheat-conducting fluid circuit and, on the other hand, the warm sourceincludes a second refrigerant/heat-conducting fluid thermal exchangerthermally coupling the main refrigerant circuit to a second secondaryheat-conducting fluid circuit.

The secondary circuits can be connected selectively, by appropriatevalves, to an external thermal exchanger, located preferably at thefront of the vehicle engine compartment, and to an internal thermalexchanger, preferably located in the vehicle passenger compartment. Byoperating these valves, the heat pump can be used either to cool thevehicle passenger compartment (in that first case, the warm source isthe external thermal exchanger and the cold source is the internalthermal exchanger) or to heat the passenger compartment (in that secondcase, the warm source is the internal thermal exchanger and the coldsource is the external thermal exchanger).

It shall be noted in the latter case that the heat pump performances arelimited by the outside air temperature. Indeed, in winter, the airtemperature limits the heat pump output, when it is used to heat thepassenger compartment. On the other hand, the freezing of the coldsource in winter can impair the operating performances of the heat pump.

The aim of this invention is to optimise the performances of a heat pumpbased thermal regulation device especially when it is used to heat anautomotive vehicle passenger compartment.

To this end, the object of this invention is a thermal regulation devicefor automotive vehicles, of the above mentioned type, characterised inthat it includes means of formation of an air flow circulating throughthe external exchanger, called outlet air flow, directed from inside theengine compartment to outside the vehicle.

According to the characteristics of several device implementation modes:

-   -   the air flow formation means include a fan;    -   the fan shall be able to rotate in a first direction to form an        air flow directed from outside the vehicle to inside the engine        compartment, called inlet air flow, and in a reverse direction        to form the outlet air flow;    -   the inlet air flow is aimed at circulating through a        heat-conducting fluid/air thermal exchanger, connected to the        engine cooling system, when this heat-conducting fluid/air        thermal exchanger is activated;    -   the fan is longitudinally inserted between the external        exchanger and a sealable front air inlet establishing        communication between the engine compartment and outside the        vehicle;    -   the fan is longitudinally inserted between the engine and the        external exchanger;    -   the device includes means of return of the outlet air flow        downstream the external exchanger, aimed at directing the outlet        air flow towards an air outlet submitted to a dynamic air        pressure lower than the pressure to which the front air inlet is        submitted;    -   the outlet air flow return means include front air inlet sealing        means.    -   the air outlet is located in a wall forming the bottom of the        engine compartment;    -   The external exchanger is a cold source refrigerant/air        exchanger;    -   The cold source includes a refrigerant/heat-conducting fluid        exchanger thermally coupling the refrigerant circuit to a        heat-conducting circuit connected to the external exchanger.

The invention will be better understood by reading the followingdescription, only given for example and made by referring to thedrawings:

FIG. 1 is a schematic view representing a heat pump assembly for athermal regulation device according to the invention;

FIG. 2 is a top schematic view of a vehicle front part equipped with athermal regulation device according to a first invention implementationmode;

FIGS. 3 and 4 are views similar to FIG. 2 representing thermalregulation devices according to a second and a third inventionimplementation modes respectively;

FIG. 4 is a side schematic view of the thermal regulation deviceaccording to the third invention implementation mode.

FIG. 1 represents a heat pump assembly, referred to as reference 10, fora thermal regulation device according to the invention and representedin several implementation modes in FIGS. 2 to 5.

In the following description, two components are called thermallycoupled when they exchange heat between each other via an appropriatethermal exchanger.

The thermal regulation device 10 includes a heat pump 12 integrating acompression type main refrigerant circuit 14, taking calories from acold source 16 to transfer them at least partially to a warm source 18.

In the described example, cold and warm sources 16 and 18 are connectedto each other by a compressor 20 (electrical and/or mechanical) and apressure relief valve 22. The refrigerant vaporises by taking the heatfrom the cold source 16. The compressor 20 pumps the vaporisedrefrigerant in and pumps it out towards a warm source where it condenseswhen cooling. The pressure relief valve 22 lets the liquid refrigerantflow towards the cold source 16 by decreasing its pressure. Therefrigerant circulation in the circuit 14 is indicated by arrows in FIG.1.

The cold source 16 includes a refrigerant/heat-conducting fluid thermalexchanger 24, called cold source exchanger, thermally coupling the mainrefrigerant circuit 14 to a heat-conducting fluid secondary circuit 26.

This secondary circuit includes a pump 28 for the heat-conducting fluidcirculation, connected to the inlet of the cold source exchanger 24. Theheat-conducting fluid circulation in the secondary circuit 26 isindicated by an arrow in FIG. 1.

The refrigerant circulating in the main circuit 14 is a traditional one.This refrigerant can be for example either a chlorinated or fluorinatedderivative of methane or ethane (Freon), or an hydrocarbon, or ammoniaor carbon dioxide. The heat-conducting fluid circulating in thesecondary circuit 26 is preferably a water/antifreeze mixture (glycol).

In the example illustrated, the secondary circuit 26 is aimed at beingconnected, in at least some usage configurations, to a thermal exchangercalled external exchanger 30, as represented in FIG. 1. The externalexchanger 30 is a heat-conducting fluid/air exchanger.

If applicable, the warm source 18 can include arefrigerant/heat-conducting fluid thermal exchanger (not represented)thermally coupling the refrigerant main circuit 14 to a heat-conductingfluid secondary circuit (not represented).

The heat pump 12 is aimed at being used, depending on the selectedoperating mode, either to cool or to heat the vehicle passengercompartment. When the heat pump is used to heat the passengercompartment, the warm source 18 brings calories to the passengercompartment.

FIG. 2 represents the front end of an automotive vehicle equipped with athermal regulation device according to the first inventionimplementation mode, referred to as the general reference 32.

The vehicle front end delimits a compartment 34 for the vehicle thermalengine 36. The external exchanger 30 is located in the vehicle enginecompartment 36.

FIG. 1 also represents a heat-conducting fluid/air thermal exchanger 38,of traditional type, called cooling exchanger, connected to the engine36 cooling system 39. For example, the external exchanger 30 and coolingexchanger 38 are located one behind the other when considering thevehicle in its longitudinal direction.

A fan 40, driven by classical motorised means, is longitudinallyinserted between the external exchanger 30 and a sealable front airinlet 42 establishing communication between the engine compartment andoutside the vehicle.

The fan 40 is controlled by traditional means making it rotate, on theone hand, in a first direction, to form an air flow directed fromoutside the vehicle to inside the engine compartment 34 (in the reversedirection to that of the thick arrows represented in FIG. 2), calledinlet air flow and, on the other hand, in a second reverse direction toform an air flow directed from inside the engine compartment 34 tooutside the vehicle (in the direction of the thick arrows represented inFIG. 2), called outlet air flow.

Therefore the fan 40 operates selectively in blowing mode (rotation inthe first direction) or aspirating mode (rotation in the seconddirection).

As long as the engine temperature is under a defined threshold (forexample for a more or less long period after starting), the coolingsystem 39, and more specifically, the cooling exchanger 38 aredeactivated (the engine cooling mean activation is generally controlledby a thermostat). The fan 40 is controlled in order to rotate in theoutlet air flow formation second direction. The vehicle passengercompartment can be then heated by the heat pump 12 operating in heatingmode in which the warm source 18 brings calories to the passengercompartment.

When the cooling exchanger 38 is activated, the fan 40 is controlledpreferably in order to rotate in the inlet air flow formation firstdirection. This inlet air flow circulates through the cooling exchanger38 by favouring thermal exchanges between the cold air flow coming fromoutside the vehicle and the heat-conducting fluid circulating in thecooling circuit 39. In this fan 40 operating mode, the front air inlet42 is at least partially open.

On the other hand, when the external exchanger 30 is activated and thethermal exchanger 38 is deactivated, the fan 40 is controlled preferablyin order to rotate in the outlet air flow formation second direction.This outlet air flow circulates through the external exchanger 30 byfavouring thermal exchanges between the air flow coming from inside thepassenger compartment 34 and the heat-conducting fluid circulating inthe secondary circuit 26.

Various exothermal components are generally located in the compartment34, especially the thermal engine. Therefore, the outlet air flow,coming from inside the passenger compartment 34, is generally warmerthan the inlet air flow. The cold source 16, thermally coupled to theexternal exchanger 30, is warmer when the external exchanger 30 is incontact with the outlet air flow (relatively warm) than when it is incontact with the air coming from outside the vehicle.

The fan 40 activation in order to generate the outlet air flow optimisesthe heat pump 12 operation and to reduce the risk of freezing of theexternal exchanger 30, especially in winter, when the heat pump 12 isused in passenger compartment heating mode.

It shall be noted that, in the first invention implementation modeillustrated in FIG. 2, the outlet air flow is drained of the enginecompartment 34 via the front air inlet 42 which is at least partiallyopen.

In FIGS. 3 to 5, thermal regulation devices are represented according tothe second and third implementation modes. In these figures, theelements similar to those of the previous figures are designated by thesame references.

In the second implementation mode, illustrated in FIG. 3, an additionalfan 44 is longitudinally inserted between the engine 36 and the externalexchanger 30.

In that case, the fan 40 is aimed at forming the inlet air flow and theadditional fan 44 is aimed at forming the outlet air flow. Thisoptimises fan 40 and 44 operation, especially in terms of flow and noiselevel, by taking into account the fact that their respective aims: toform the inlet air flow for the first fan 40 and the outlet air flow forthe second fan 44.

When the additional fan 44 is activated to generate the outlet air flow(heat pump 12 operating in heating mode), the fan 40 is generallydeactivated (cold engine). When the fan 40 is activated to generate theinlet air flow (cooling exchanger 38 activated), the additional fan 44is generally deactivated (heat pump 12 deactivated).

In the third implementation mode, illustrated in FIGS. 4 and 5, theoutlet air flow is sent back, downstream the external exchanger 30, toan air outlet 46 submitted to a dynamic air pressure lower than thepressure to which the front inlet 42 is submitted. Preferably, the airoutlet 46 is located in an approximately horizontal wall 48 forming thebottom of the engine compartment 34.

Front inlet 42 sealing means 50, such as traditional controlled valves,allow, by at least partially sealing the inlet 42, to send the outletair flow back downstream the external exchanger in an approximatelyvertical direction easing the air discharge by the outlet 46.

The invention is not limited to the implementation modes describedhereabove.

In particular, the fan 40 in the first and third implementation modes isnot necessarily shared by the external exchanger 30 and the coolingexchanger 38. A fan specific to the external exchanger 30 can be added.

On the other hand, in the case of a traditional two-way cycle heat pump(refrigerant two-way circulation), the heat-conducting fluid/airexchanger 30 and the secondary circuit 26 can be removed. Arefrigerant/air exchanger located in place of the heat-conductingfluid/air exchanger 30 and having the same function will be used as acold source exchanger 24.

Lastly, the engine 36 aiming at powering the vehicle is not necessarilya thermal engine and can be of another type, for example of electrictype.

1. A thermal regulation device for automotive vehicles, comprising: aheat pump including a compression refrigerant circuit taking caloriesfrom a cold source to transfer them at least partially towards a warmsource; an external exchanger located in the vehicle engine compartmentand in thermal exchange with the cold source; and a means of formationof an air flow circulating through the external exchanger, the air flowincluding an outlet air flow directed from inside the engine compartmentto outside the vehicle in an outlet direction while an enginecompartment temperature is below a threshold value and an inlet air flowdirected front outside the vehicle to inside the engine compartment inan inlet direction while the engine compartment temperature is above thethreshold value.
 2. A device according to claim 1, characterized in thatair flow formation means includes a fan.
 3. A device according to claim2, characterized in that the fan rotates in a first direction to formthe inlet air flow and in a reverse direction to form the outlet airflow.
 4. A device according to claim 3, characterized in that the inletair flow circulate through a the external exchanger when the enginecompartment temperature is above the threshold value.
 5. A deviceaccording to claim 4, characterized in that the fan is longitudinallyinserted between the external exchanger and a sealable front air inletestablishing communication between the engine compartment and outsidethe vehicle.
 6. A device according to claim 4, characterized in that thefan is longitudinally inserted between the engine and the externalexchanger.
 7. A device according to claim 6, further comprising a meansof return of the outlet air flow downstream the external exchanger,dedicated to direct the outlet air flow towards an air outlet submittedto a dynamic air pressure lower than the pressure to which the frontinlet is submitted.
 8. A device according to claim 7, characterized inthat the outlet air flow return means includes a front air inlet sealingmeans.
 9. A device according to claim 8, characterized in that the airoutlet is located in a wall forming the bottom of the enginecompartment.
 10. A device according to claim 9, characterized in thatthe external exchanger is a rifrigerant/air cold source exchanger.
 11. Adevice according to any claim 9, characterized in that the cold sourceincludes a refrigerant/heat-conducting fluid exchanger thermallycoupling the refrigerant circuit to a heat-conducting fluid circuitconnected to the external exchanger.
 12. A device according to claim 1,wherein the external exchanger is in fluid communication with an enginecooling system.
 13. A device according to claim 12, wherein the externalexchanger is in thermal exchange with the engine cooling system whitethe engine compartment temperature is above the threshold value.
 14. Athermal regulation device for automotive vehicles, comprising a heatpump including a compression refrigerant circuit taking calories coldsource to transfer them at least partially towards a warm source; anexternal exchanger located in the vehicle engine compartment and inthermal exchange with the cold source; a means of formation of an airflow circulating through the external exchanger, the air flow includingan outlet air flow directed from inside the engine compartment tooutside the vehicle in an outlet direction while an engine compartmenttemperature is below a threshold value and an inlet air flow directedfrom outside the vehicle to inside the engine compartment in an inletdirection while the engine compartment temperature is above thethreshold value; and a means of return of the outlet air flow downstreamthe external exchanger to direct the outlet air flow towards an airoutlet submitted to a dynamic air pressure lower than the pressure towhich the front inlet is submitted.
 15. A device according to claim 14,characterized in that the outlet air flow return means includes a frontair inlet sealing means.
 16. A device according to claim 15,characterized in that the air outlet is located in a wall forming thebottom of the engine compartment.
 17. A device according to claim 16,characterized in that the external exchanger is a refrigerant/air coldsource exchanger.
 18. A device according to claim 17, characterized inthat the cold source includes a refrigerant/heat-conducting fluidexchanger thermally coupling the refrigerant circuit to aheat-conducting fluid circuit connected to the external exchanger.